Method for strengthening high-concentration slurry by kerosene modified biochar

Abstract

The present application belongs to the technical field of coal water slurry preparation, and discloses a method for preparing high-concentration slurry by using kerosene modified biochar, which comprises the following steps: mixing and stirring kerosene and biochar to form a hydrophobic coating layer on the surface of biochar particles, thereby obtaining kerosene modified biochar; the hydrophobic layer can effectively block the water absorption channel of the pores of biochar, thereby inhibiting water absorption and thickening from the source; then, coal powder and a dispersing agent are added to the modified biochar and uniformly mixed to obtain a premix, so that the kerosene modified biochar, the coal powder and the dispersing agent are fully contacted, thereby avoiding agglomeration in subsequent slurry preparation; finally, water is added to adjust the solid content to the target concentration and high-speed stirring is performed, thereby forming a high-concentration biochar-coal-water multi-component slurry. The method realizes mild hydrophobic modification of the surface of biochar by using low-cost kerosene, and is free of corrosion and pollution. Compared with the unmodified biochar slurry, the maximum slurry concentration of the modified multi-component slurry is significantly improved, and the apparent viscosity is significantly reduced and the flowability is significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of coal-water slurry preparation technology, specifically a method for enhancing high-concentration slurry formation with kerosene-modified biochar. Background Technology

[0002] Biochar has a highly porous structure and a large specific surface area, making it prone to absorbing large amounts of water when used in coal-water slurry. This leads to increased slurry viscosity, decreased fluidity, and difficulty in achieving the maximum slurry concentration. Conventional physical modification, acid-base modification, and oxidant modification methods suffer from problems such as equipment corrosion, environmental pollution, high costs, and rapid decay of modification effects, making them difficult to apply industrially.

[0003] Surface modification is an effective way to improve the hydrophobicity of biochar, reduce water absorption, and improve slurry formation performance. However, commonly used modifiers such as surfactants, polymers, and silane coupling agents are expensive, have weak binding force with biochar, are easily desorbed in the slurry, and have poor long-term stability. Kerosene is widely available, low in cost, and has good hydrophobic effect. It can form a uniform hydrophobic coating layer on the surface of biochar, preventing water from entering the pores, reducing interparticle friction, and thus improving slurry concentration and fluidity.

[0004] Currently, there are few technologies for surface modification of biochar using kerosene to enhance high-concentration slurry formation, and systematic research on optimal dosage, modification mechanisms, and rheological control is lacking. Excessive kerosene can easily form interparticle oil bridges, leading to increased viscosity; insufficient dosage results in insignificant modification effects. Summary of the Invention

[0005] This invention provides a method for enhancing high-concentration slurry formation with kerosene-modified biochar, which solves the problems of low concentration and poor fluidity of biochar and coal multi-element slurry.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for enhancing high-concentration slurry formation with kerosene-modified biochar, comprising the following steps: hydrophobic modification of the biochar surface with kerosene: mixing and stirring kerosene with biochar to form a hydrophobic coating layer on the surface of biochar particles with kerosene, thereby obtaining kerosene-modified biochar. Coal powder and dispersant are added to the kerosene-modified biochar and mixed evenly to obtain a premix. Water is added to the premixed material, the solid content is adjusted to the target concentration, and the mixture is stirred at high speed to obtain a high-concentration biochar-coal-water multi-component slurry.

[0007] According to one embodiment of the present invention, the biochar is straw biochar with a pyrolysis temperature of 400-475℃.

[0008] According to one embodiment of the present invention, the amount of kerosene added is 0.5%-1.0% of the total dry basis mass of biochar, coal powder and dispersant.

[0009] According to one embodiment of the present invention, the amount of kerosene added is 0.6%-0.9% of the total dry basis mass of biochar, coal powder and dispersant.

[0010] According to one embodiment of the present invention, the kerosene and biochar are mixed and stirred at a speed of 500-900 rpm for a time of 5-15 min.

[0011] According to one embodiment of the present invention, the amount of dispersant added is 0.5%-1.5% of the total dry basis mass of biochar, coal powder and dispersant.

[0012] According to one embodiment of the present invention, the target solid content is 60%-65%.

[0013] According to one embodiment of the present invention, after adding water, the high-speed stirring speed is 800-1200 rpm and the time is 10-20 min.

[0014] According to one embodiment of the present invention, the coal powder is Shenhua coal, and the mass ratio of biochar to coal powder is 1:5 to 1:15.

[0015] According to one embodiment of the present invention, the method further includes a step of testing the slurry-forming properties of the obtained multi-component slurry: measuring the maximum slurry-forming concentration of the unmodified biochar multi-component slurry and the kerosene-modified biochar multi-component slurry respectively, and measuring the apparent viscosity of the kerosene-modified biochar multi-component slurry under specified shear rate and temperature conditions.

[0016] Compared with existing technologies, this invention has the following beneficial effects: This invention provides a method for enhancing high-concentration slurry formation with kerosene-modified biochar. By mixing and stirring kerosene and biochar, a hydrophobic coating layer is formed on the surface of the biochar particles, resulting in kerosene-modified biochar. This hydrophobic layer effectively blocks the water absorption channels in the biochar pores, inhibiting water absorption and thickening at the source. Then, coal powder and a dispersant are added to the modified biochar and mixed evenly to obtain a premix, ensuring sufficient contact between the kerosene-modified biochar, coal powder, and dispersant, preventing agglomeration during subsequent slurry preparation. Finally, water is added to adjust the solid content to the target concentration and the mixture is stirred at high speed to form a high-concentration biochar-coal-water multi-element slurry. This method utilizes low-cost kerosene to achieve gentle hydrophobic modification of the biochar surface, without corrosion or pollution. Compared to unmodified biochar slurry, the maximum slurry concentration of the modified multi-element slurry is significantly increased, while the apparent viscosity is significantly reduced and the fluidity is significantly improved. When the amount of kerosene added is within a suitable range, a continuous and uniform hydrophobic film can be formed; excessive kerosene will create oil bridges, leading to a rebound in viscosity. By precisely controlling the quantity, the viscosity can be stably controlled while increasing the slurry concentration, thus overcoming the technical challenge of high slurry viscosity and poor fluidity caused by the well-developed pores and easy water absorption of biochar. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart of a method for enhancing high-concentration slurry formation with kerosene-modified biochar according to the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0021] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0022] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0023] Biochar, with its highly porous structure and large specific surface area, readily absorbs water when used in coal-water slurry, leading to increased viscosity, decreased fluidity, and difficulty in achieving the maximum slurry concentration. Conventional physical modification and acid-base modification methods suffer from problems such as equipment corrosion, environmental pollution, and high costs. Surface modification can improve the hydrophobicity of biochar, but commonly used modifiers are expensive and easily desorbed. Kerosene, on the other hand, is widely available, inexpensive, and has good hydrophobic properties, forming a uniform hydrophobic coating layer on the biochar surface. This invention provides a method for enhancing high-concentration slurry formation using kerosene-modified biochar. By precisely controlling the kerosene dosage, it significantly increases the slurry concentration of multi-component slurries and improves fluidity.

[0024] like Figure 1As shown, this embodiment of the invention provides a method for enhancing high-concentration slurry formation with kerosene-modified biochar, comprising the following steps: Kerosene surface hydrophobic modification of biochar: Kerosene and biochar are mixed and stirred so that kerosene forms a hydrophobic coating layer on the surface of biochar particles, thus obtaining kerosene-modified biochar. Coal powder and dispersant are added to the kerosene-modified biochar and mixed evenly to obtain a premix. Water is added to the premixed material, the solid content is adjusted to the target concentration, and the mixture is stirred at high speed to obtain a high-concentration biochar-coal-water multi-component slurry.

[0025] Kerosene and biochar are mixed and stirred to form a hydrophobic coating on the surface of the biochar particles, resulting in kerosene-modified biochar. This hydrophobic layer effectively blocks the water absorption channels in the biochar pores, inhibiting water absorption and thickening at the source. Then, coal powder and a dispersant are added to the modified biochar and mixed evenly to obtain a premix, ensuring sufficient contact between the kerosene-modified biochar, coal powder, and dispersant, preventing agglomeration during subsequent pulping. Finally, water is added to adjust the solid content to the target concentration, and the mixture is stirred at high speed to form a high-concentration biochar-coal-water multi-component slurry. This method utilizes low-cost kerosene to achieve gentle hydrophobic modification of the biochar surface, without corrosion or pollution. Compared to the unmodified biochar slurry, the maximum slurry concentration of the modified multi-component slurry is significantly increased, while the apparent viscosity is significantly reduced and the flowability is significantly improved. When the amount of kerosene added is within an appropriate range, a continuous and uniform hydrophobic film can be formed; excessive kerosene will create oil bridging, leading to a rebound in viscosity. By precisely controlling the quantity, the viscosity can be stably controlled while increasing the slurry concentration, thus overcoming the technical challenge of high slurry viscosity and poor fluidity caused by the well-developed pores and easy water absorption of biochar.

[0026] The detailed steps are as follows: Step S1: Selection and pretreatment of biochar raw materials Straw biochar prepared by oxygen-limited pyrolysis at 400–475℃ was selected as the modification raw material. Biochar pyrolyzed within this temperature range has a well-developed pore structure and a moderate number of surface active sites, making it a preferred raw material for hydrophobic modification of kerosene. The biochar was crushed, ground, and sieved to obtain uniformly sized biochar powder, which was then placed in a desiccator for later use to prevent moisture absorption from affecting the modification effect. This drying pretreatment prevents the biochar's inherent moisture from interfering with the uniformity of kerosene coating.

[0027] Step S2: Hydrophobic modification of kerosene surface Weigh a measured amount of dried biochar and add kerosene at 0.5%–1.0% of the total dry-basis solid mass (total dry-basis mass of biochar, coal powder, and dispersant), with an optimal dosage of 0.8%. Add the kerosene and biochar to a mixing container, turn on the stirrer, and stir at a constant speed of 700 rpm for 10 minutes to allow the kerosene to spread rapidly on the surface of the biochar particles, forming a continuous, uniform, and stable hydrophobic coating layer, thus obtaining kerosene-modified biochar. This hydrophobic layer can effectively block the water absorption channels in the pores, inhibiting the thickening of the biochar by water absorption at the source.

[0028] Step S3: Coal and dispersant compound premix To the aforementioned kerosene-modified biochar system, a graded coal sample was added at a biochar to Shenhua coal mass ratio of 1:9, along with 1% (by dry basis) of a dispersant (such as sodium naphthalene-based formaldehyde sulfonate). The mixture was stirred at 700 rpm for 10 minutes to ensure thorough and uniform mixing of the coal, dispersant, and modified biochar, yielding a premix. Optimizing the particle size distribution increases the slurry bulk density, while the dispersant reduces the solid-liquid interfacial tension, thus enhancing the kerosene modification effect.

[0029] Step S4: Add water to adjust the slurry and disperse at high speed Slowly add a measured amount of ultrapure water to the premix to precisely adjust the solid content of the slurry to 63%. Increase the stirring speed to 1000 rpm and stir at high speed for 15 minutes to break up particle agglomeration and form a stable and homogeneous system of hydrophobic modified biochar, coal, dispersant, and water to obtain a high-concentration biochar-coal-water multi-element slurry.

[0030] Step S5: Pulping performance testing The resulting multi-component slurry was tested for its slurry-forming properties. The maximum slurry concentrations of the unmodified biochar multi-component slurry and the kerosene-modified biochar multi-component slurry were measured, and the apparent viscosity of the kerosene-modified biochar multi-component slurry was measured under specified shear rates and temperatures. The modification effect was verified by comparison.

[0031] Optimal doping verification and performance control Multiple sets of kerosene content control experiments were conducted (e.g., 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%), and the apparent viscosity was tested after pulping according to the above steps. The results showed that at 0.5%–0.7%, the coating became more complete with increasing kerosene content, and the viscosity continuously decreased; at 0.8%, the viscosity reached its lowest value, and the fluidity was optimal; at 0.9%–1.0%, excessive kerosene formed oil bridges between particles, leading to a rebound in viscosity. Therefore, strictly controlling the kerosene content within the range of 0.6%–0.9%, with 0.8% being optimal, achieves both optimal concentration and viscosity.

[0032] Example 1 (kerosene content 0.5%) Self-made pyrolytic biochar at 450℃ was selected as the modified raw material. 5g of biochar was weighed and placed in a stirring container. Kerosene was added at 0.5% of the total dry solids mass, and the mixture was stirred at 700 rpm for 10 minutes to form a preliminary hydrophobic coating layer on the surface of the biochar particles, resulting in kerosene-modified biochar. Graded Shenhua coal (biochar to Shenhua coal mass ratio 1:9) and 1% of naphthalene-based sodium formaldehyde sulfonate dispersant (dry solids mass) were added to the kerosene-modified biochar. The mixture was stirred at 700 rpm for 10 minutes to ensure thorough and uniform mixing of the coal, dispersant, and modified biochar, resulting in a premix. Ultrapure water was added to the premix to adjust the slurry solids content to 63%, and the mixture was stirred at 1000 rpm for 15 minutes to obtain a kerosene-modified biochar multi-component slurry. The apparent viscosity of the slurry in this embodiment was 1447.62 mPa·s, indicating a relatively weak modification effect.

[0033] Example 2 (kerosene content 0.6%) Self-made pyrolytic biochar at 450℃ was selected as the modified raw material. 5g of biochar was weighed and placed in a stirring container. Kerosene was added at 0.6% of the total dry solids mass, and the mixture was stirred at 700 rpm for 10 minutes to form a hydrophobic coating layer on the surface of the biochar particles, resulting in kerosene-modified biochar. Graded Shenhua coal (biochar to Shenhua coal mass ratio 1:9) and 1% of naphthalene-based sodium formaldehyde sulfonate dispersant (dry solids mass) were added to the kerosene-modified biochar. The mixture was stirred at 700 rpm for another 10 minutes to ensure thorough and uniform mixing of the coal, dispersant, and modified biochar, resulting in a premix. Ultrapure water was added to the premix to adjust the slurry solids content to 63%, and the mixture was stirred at 1000 rpm for 15 minutes to obtain a kerosene-modified biochar multi-component slurry. Testing showed that the kerosene coating effect was improved, and the apparent viscosity of the slurry was significantly lower than in Example 1.

[0034] Example 3 (kerosene content 0.7%) Self-made pyrolytic biochar at 450℃ was selected as the modified raw material. 5g of biochar was weighed and placed in a stirring container. Kerosene was added at 0.7% of the total dry solids mass, and the mixture was stirred at 700 rpm for 10 minutes to form a hydrophobic coating layer on the surface of the biochar particles, resulting in kerosene-modified biochar. Graded Shenhua coal (biochar to Shenhua coal mass ratio 1:9) and 1% of naphthalene-based sodium formaldehyde sulfonate dispersant (dry solids mass) were added to the kerosene-modified biochar. The mixture was stirred at 700 rpm for another 10 minutes to ensure thorough and uniform mixing of the coal, dispersant, and modified biochar, resulting in a premix. Ultrapure water was added to the premix to adjust the slurry solids content to 63%, and the mixture was stirred at 1000 rpm for 15 minutes to obtain a kerosene-modified biochar multi-component slurry. Testing showed that the hydrophobic layer on the biochar surface was more complete, particle water absorption was further reduced, and the slurry viscosity continued to decrease.

[0035] Example 4 (kerosene content 0.8%) Self-made pyrolytic biochar at 450℃ was selected as the modified raw material. 5g of biochar was weighed and placed in a stirring container. Kerosene was added at 0.8% of the total dry solids mass, and the mixture was stirred at 700 rpm for 10 minutes to form a continuous, uniform, and stable hydrophobic film on the surface of the biochar particles, thus obtaining kerosene-modified biochar. Graded Shenhua coal (biochar to Shenhua coal mass ratio 1:9) and 1% of naphthalene-based sodium formaldehyde sulfonate dispersant (dry solids mass) were added to the kerosene-modified biochar. The mixture was stirred at 700 rpm for another 10 minutes to ensure thorough and uniform mixing of the coal, dispersant, and modified biochar, resulting in a premix. Ultrapure water was added to the premix to adjust the slurry solids content to 63%, and the mixture was stirred at 1000 rpm for 15 minutes to obtain a kerosene-modified biochar multi-component slurry. Tests showed that the apparent viscosity of the slurry in this embodiment was reduced to a minimum of 694.04 mPa·s, and the maximum slurry concentration was increased from 61.6% in the unmodified form to 64.2%, with significant improvements in slurry fluidity and stability.

[0036] Example 5 (kerosene content 0.9%) Self-made pyrolytic biochar at 450℃ was selected as the modified raw material. 5g of biochar was weighed and placed in a stirring container. Kerosene was added at 0.9% of the total dry solids mass, and the mixture was stirred at 700 rpm for 10 minutes to form a hydrophobic coating layer on the surface of the biochar particles, resulting in kerosene-modified biochar. Graded Shenhua coal (biochar to Shenhua coal mass ratio 1:9) and 1% of naphthalene-based sodium formaldehyde sulfonate dispersant (dry solids mass) were added to the kerosene-modified biochar. The mixture was stirred at 700 rpm for another 10 minutes to ensure thorough and uniform mixing of the coal, dispersant, and modified biochar, resulting in a premix. Ultrapure water was added to the premix to adjust the slurry solids content to 63%, and the mixture was stirred at 1000 rpm for 15 minutes to obtain a kerosene-modified biochar multi-component slurry. Testing revealed that because the kerosene dosage exceeded the optimal range, oil bridges formed between the particles, encapsulating free water and reducing lubrication, leading to an increase in the apparent viscosity of the slurry.

[0037] Example 6 (kerosene content 1.0%) Self-made pyrolytic biochar at 450℃ was selected as the modified raw material. 5g of biochar was weighed and placed in a stirring container. Kerosene was added at 1.0% of the total dry solids mass, and the mixture was stirred at 700 rpm for 10 minutes to form a hydrophobic coating layer on the surface of the biochar particles, resulting in kerosene-modified biochar. Graded Shenhua coal (biochar to Shenhua coal mass ratio 1:9) and 1% of naphthalene-based sodium formaldehyde sulfonate dispersant (based on dry solids mass) were added to the kerosene-modified biochar. The mixture was stirred at 700 rpm for another 10 minutes to ensure thorough and uniform mixing of the coal, dispersant, and modified biochar, resulting in a premix. Ultrapure water was added to the premix to adjust the slurry solids content to 63%, and the mixture was stirred at 1000 rpm for 15 minutes to obtain a kerosene-modified biochar multi-component slurry. Testing showed that excessive kerosene exacerbated oil bridging, significantly reduced slurry fluidity, and continuously increased apparent viscosity.

[0038] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the scope of the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0039] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for enhancing high-concentration slurry formation with kerosene-modified biochar, characterized in that, Includes the following steps: Kerosene surface hydrophobic modification of biochar: Kerosene and biochar are mixed and stirred so that kerosene forms a hydrophobic coating layer on the surface of biochar particles, thus obtaining kerosene-modified biochar. Coal powder and dispersant are added to the kerosene-modified biochar and mixed evenly to obtain a premix. Water is added to the premixed material, the solid content is adjusted to the target concentration, and the mixture is stirred at high speed to obtain a high-concentration biochar-coal-water multi-component slurry.

2. The method for enhancing high-concentration slurry formation with kerosene-modified biochar according to claim 1, characterized in that, The biochar is straw biochar, with a pyrolysis temperature of 400-475℃.

3. The method for enhancing high-concentration slurry formation with kerosene-modified biochar according to claim 1, characterized in that, The amount of kerosene added is 0.5%-1.0% of the total dry basis mass of biochar, coal powder and dispersant.

4. The method for enhancing high-concentration slurry formation with kerosene-modified biochar according to claim 3, characterized in that, The amount of kerosene added is 0.6%-0.9% of the total dry basis mass of biochar, coal powder, and dispersant.

5. The method for enhancing high-concentration slurry formation with kerosene-modified biochar according to claim 1, characterized in that, The kerosene and biochar are mixed and stirred at a speed of 500-900 rpm for 5-15 minutes.

6. The method for enhancing high-concentration slurry formation with kerosene-modified biochar according to claim 1, characterized in that, The amount of dispersant added is 0.5%-1.5% of the total dry basis mass of biochar, coal powder and dispersant.

7. The method for enhancing high-concentration slurry formation with kerosene-modified biochar according to claim 1, characterized in that, The target solid content is 60%-65%.

8. The method for enhancing high-concentration slurry formation with kerosene-modified biochar according to claim 1, characterized in that, After adding water, stir at a high speed of 800-1200 rpm for 10-20 minutes.

9. The method for enhancing high-concentration slurry formation with kerosene-modified biochar according to claim 1, characterized in that, The coal powder is Shenhua coal, and the mass ratio of biochar to coal powder is 1:5 to 1:

15.

10. The method for enhancing high-concentration slurry formation with kerosene-modified biochar according to claim 1, characterized in that, It also includes a step of testing the slurry-forming properties of the obtained multi-component slurry: measuring the maximum slurry concentration of the unmodified biochar multi-component slurry and the kerosene-modified biochar multi-component slurry respectively, and measuring the apparent viscosity of the kerosene-modified biochar multi-component slurry under specified shear rates and temperatures.

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